Bag for air bag system and manufacturing method thereof

Abstract

A method of manufacturing a bag for an air bag system has the steps of (a) securing together a first base cloth having a gas inlet and a second base cloth along a periphery thereof, (b) forming a main bag and at least one auxiliary bag so that the at least one auxiliary bag is located between the main bag and the periphery, and (c) turning the first base cloth and the second base cloth inside out via the gas inlet. A bag is provided by the method and has a main bag and at least one auxiliary bag as component parts.

What is claimed is: 
     
       1. A method of manufacturing a bag for an air bag system, said method comprising the steps of: (a) securing together a first base cloth having a gas inlet and a second base cloth along a periphery thereof after stacking said first base cloth and said second base cloth so that said periphery has a first rupture strength;   (b) forming a main bag and at least one auxiliary bag immediately after securing together said first base cloth and said second base close along the periphery thereof so that said at least one auxiliary bag is located between said main bag and said periphery and a division between said main bag and said auxiliary bag has a second rupture strength which is less than said first rupture strength; and   (c) turning the first base cloth and the second base cloth inside out via the gas inlet after forming said main bag and at least one auxiliary bag so that said at least one auxiliary bag can be located interiorly of said main bag.   
     
     
       2. The method as claimed in claim 1, wherein said securing includes a step of stitching the first and the second base cloths together. 
     
     
       3. The method as claimed in claim 1, wherein said securing includes a step of bonding the first and the second base cloths together. 
     
     
       4. The method as claimed in claim 1, wherein said securing includes a step of welding the first and the second base cloths together. 
     
     
       5. The method as claimed in claim 1, wherein said step (b) includes a step of (b-1) securing the first and the second base cloths together in at least one position inwardly from said periphery so that said at least one position inwardly from said periphery is secured at said second rupture strength.   
     
     
       6. The method as claimed in claim 5, wherein said step (b-1) includes a step of securing the first and the second base cloths together and forming a plurality of auxiliary bags. 
     
     
       7. The method as claimed in claim 5, wherein: said step (a) includes a step of stitching the first and the second base cloths together by a first thread of a predetermined rupture strength; and   said step (b-1) includes a steps of stitching the first and the second base cloths together by a second thread having a predetermined rupture strength less than that of the first thread.   
     
     
       8. A bag for an air bag system comprising: a main bag having a gas inlet and defined by secured portions which directly connect a first base cloth and a second base cloth and have a first rupture strength; and   at least one auxiliary bag located interiorly of said main bag and defined by secured portions which directly connect said first base cloth and said second base cloth and have a second rupture strength which is less than said first rupture strength.   
     
     
       9. The bag as claimed in claim 8, wherein said secured portions are joined by being stitched. 
     
     
       10. The bag as claimed in claim 8, wherein said joined portions are secured by being bonded. 
     
     
       11. The bag as claimed in claim 8, wherein said secured portions are joined by being welded. 
     
     
       12. An air bag system comprising: deceleration detecting unit detecting deceleration exerted on an automobile;   a control unit generating a control signal when said deceleration detecting unit detects a deceleration larger than a predetermined level;   a gas releasing unit releasing a gas when it receives said control signal; and   a bag including a main bag having a gas inlet and defined by secured portions which directly connect a first base cloth and a second base cloth and have first rupture strength, and at least one auxiliary bag located interiorly of said main bag and defined by secured portions which directly connect said first and second base cloths and have a second rupture strength which is less than said first rupture strength.   
     
     
       13. A bag for an air bag system comprising: a main bag having a gas inlet and defined by first secured portions which directly connect a first base cloth and a second base cloth and have a first rupture strength; and   at least one auxiliary bag located interiorly of said main bag and defined by second secured portions which directly connect said first base cloth, said second base cloth and a part of said first secured portions and have a second rupture strength which is less than said first strength.